1. Field of the Invention
This invention relates broadly to the field of container making, and more specifically to blow molded plastic bottles, such as the PET bottles that are in common use today for packaging soft drinks such as soda.
2. Description of the Related Technology
During the last twenty-five years or so, there has been a dramatic shift in the packaging of beverages, such as bottled water and soft drinks, away from glass containers and toward plastic containers. Polyethylene terephthalate (PET) is in wide use throughout the world for such containers because it exhibits such preferred characteristics as high toughness, light weight, high transparency, high pressure resistance and acts as a good gas barrier.
The packaging industry is highly competitive, and economic pressure exists to encourage lightweighting (e.g. minimizing the amount of plastic material that is used) the container as much as possible. As a practical matter, the amount of lightweighting that can be achieved is limited by the necessary design strength of the container. In particular, each container must have a certain minimum axial strength, which refers to strength against forces that may be applied in a direction that is parallel to the axis of the container, and a minimum hoop strength, which is defined as strength against forces that may be applied circumferentially against the outer wall of the container. Another factor that is important is the rigidity that the container exhibits against deformation as a result of being gripped or squeezed.
Typically, such containers have a central smooth label area to which a label is pasted or applied by means of a pressure sensitive adhesive. One problem that sometimes exists is that condensation can collect between the container and the label, thereby acting to weaken the bond and delaminate the label from the container. Any improvement that will tend to reduce or eliminate this problem should be well received in the industry.
In general, containers tend to be stabilized against rocking and tipping if they have support feet that provide a large foot surface area for supporting the container on an underlying surface. It is easier to provide for a large amount of foot surface area by minimizing the number of support feet, because this also minimizes the number of grooves that separate the feet on the bottom of the container. Unfortunately, minimizing the number of support feet and associated grooves also tends to reduce the axial strength and hoop strength of the container wall in the area that is immediately above the support feet.
A need exists for an improved container design that optimizes strength and lightweighting potential, that reduces the potential for condensate to collect between the container and a label, and that maximizes foot surface area without materially reducing the axial strength and hoop strength of the container wall in the area that is immediately above the support feet.